We propose to conduct secondary data analysis to examine the longitudinal relationships among incarceration, substance use, and STI/HIV risk. In 2008 more than 2 million adults in the United States were behind bars. Jail and prison inmates, often among the most economically and socially disadvantaged segment of our population, also face disproportionate infectious disease risk. Sexually transmitted infections (STIs), including HIV, cluster in incarcerated populations. Prisoners'spouses, sexual partners, and other members of their sexual networks also experience high risk of infection. In some populations, incarceration rates are staggering and communities experience continual migrations of substantial segments of the population in and out of the criminal justice system. STIs and HIV thrive on sexual network disruption. Thus, disruption of sexual networks due to incarceration may lead to new, multiple, and concurrent sexual partnerships, all of which fuel STI/HIV transmission. Does the disruptive effect of incarceration contribute to STI/HIV risk? Or, do adverse economic and social factors such as drug use-that may have led to the incarceration-drive high sexual risk and STI/HIV levels among current and former inmates and members of their sexual networks? We do not know- the strong association between incarceration and STI/HIV remains unexplained and warrants investigation. Using the National Longitudinal Study of Adolescent Health, we will apply advanced statistical procedures to measure the effects of adolescent substance use on multiple (e 2) sexual partnerships and biologically confirmed infection with chlamydia, gonorrhea, or trichomoniasis in adulthood. We will evaluate the degree to which incarceration in adulthood mediates the relationship between substance use and STI/HIV risk. The STIs we will study have clear public health relevance not only because they contribute to substantial morbidity but because they increase HIV transmission. The specific aims of the proposed study are to: Aim 1: Measure longitudinal associations between adolescent substance use and multiple sexual partnerships and STI in adulthood and evaluate whether race or criminal justice involvement moderates the relationships. Aim 2: Measure associations between incarceration and multiple sexual partnerships and STI in adulthood. Aim 3: Evaluate the degree to which incarceration in adulthood mediates the relationships between adolescent substance use and multiple sexual partnerships and STI in adulthood. This research is innovative in its unique synthesis of and public health relevance to STI and drug dependence epidemiology and the criminal justice field. The proposed analyses are designed to provide an empirical basis for development of larger R01s to (1) examine the effect of disruptions in intimate partnerships at the time of incarceration on STI/HIV risk and (2) test the effectiveness of STI/HIV prevention interventions that aim to mitigate the deleterious effects of incarceration and drug dependence. PUBLIC HEALTH RELEVANCE: By identifying ways that incarceration and substance use work independently and together to increase STI/HIV risk, we will better understand whether scarce prevention resources should be prioritized for: substance use prevention and treatment, development and implementation of interventions that mitigate the disruptive effects of incarceration, or both. Since more than 2 million adults are in United States jails and prisons at any given time, even modest effects of incarceration on STI/HIV risk have significant ramifications at the population level. Hence, interventions effective in reducing incarceration-related STI/HIV transmission that may be developed, in part, based on this research would prevent substantial numbers of new infections.